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Ischemic Mitral Regurgitation: Chordal-Sparing Mitral Valve Replacement
Ischemic Mitral Regurgitation: Chordal-Sparing Mitral Valve Replacement Tirone E. David, MD
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n 1964, Lillehei and colleagues introduced the concept of preservation of the attachments between the papillary muscles and mitral annulus during mitral valve replacement to prevent postoperative left ventricular dysfunction.1 This concept was challenged by other investigators and largely abandoned until 1983 when we reexamined the issue and
Division of Cardiovascular Surgery of Peter Munk Cardiac Centre at Toronto General Hospital and University of Toronto, Toronto, Ontario Canada. Dr. David reports receiving lecture fees from Medtronic and St. Jude Medical. Address reprint requests to Tirone E. David, MD, 200 Elizabeth Street 4N457, Toronto, Ontario M5G 2C4, Canada. E-mail: tirone.david@ uhn.ca
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1522-2942/$-see front matter © 2012 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1053/j.optechstcvs.2012.04.003
found that the attachments between the papillary muscles and mitral annulus were important for postoperative ventricular function in patients with mitral insufficiency.2 This can be accomplished when the mitral insufficiency is corrected by means of mitral valve repair or mitral valve replacement with preservation of the chordae tendineae.2 We also found that mitral valve replacement with preservation of chordae tendineae reduced operative mortality and enhanced late survival in patients with ischemic mitral insufficiency.3 This article describes the technique we have used to preserve the attachments between the papillary muscles and mitral annulus during mitral valve replacement for ischemic mitral insufficiency.
Ischemic mitral regurgitation: Chordal-sparing mitral valve replacement
Operative Technique
Figure 1 Because patients with ischemic mitral insufficiency frequently require concomitant myocardial revascularization, full median sternotomy is the usual approach to the heart. Cardiopulmonary bypass is established by cannulating the ascending aorta and both cavae through the right atrium. During the aortic clamping, the myocardium is protected with cold blood cardioplegia delivered intermittently through the aortic root and coronary sinus. The coronary arteries are bypassed before repairing or replacing the incompetent mitral valve. The left atrium is opened widely starting at the interatrial groove and extending to the dome of the atrium behind the superior vena cava and inferiorly toward the left inferior pulmonary vein and parallel to the coronary sinus. IVC ⫽ inferior vena cava; SVC ⫽ superior vena cava.
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Figure 2 The majority of patients with ischemic mitral regurgitation have thin and pliable mitral valve leaflet. If the mitral valve is to be replaced and the mitral annulus is dilated, a triangular resection of the anterior leaflet (A) is performed, leaving all chordae tendineae attached to the ventricular surface of the remnants of the anterior leaflet (B).
Ischemic mitral regurgitation: Chordal-sparing mitral valve replacement
Figure 3 Multiple interrupted inverting sutures of 2-0 polyester with pledgets are passed through the mitral annulus approximately 3-4 mm from the free margins of the posterior leaflet. It is important to keep all chordae tendineae taut but not excessively so as to apply undue tension on the papillary muscles.
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Figure 4 In the commissural areas the sutures are passed through the annulus first and then through the remnants of the anterior leaflet 5-9 mm from its free margin to avoid excessive tension of the strut chords that are inserted on the ventricular side of the anterior leaflet, a few millimeters from the free margin (A). If the remnants cannot be folded on the annulus safely because the strut chords are too short, it is safer to resect the anterior leaflet entirely and preserve only the posterior leaflet and some commissural chordae (B).
Ischemic mitral regurgitation: Chordal-sparing mitral valve replacement
Figure 5 Once all annular sutures are through the mitral annulus and leaflets, they are then passed through the sewing ring of a prosthetic heart valve. The prosthetic heart valve must not be larger than the annulus and it is safer to be slightly smaller than the size of the mitral annulus.
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Figure 6 The sutures are evenly distributed in the sewing ring of mechanical valve and the ends are tied (A). If a bileaflet mechanical valve is used, the leaflets should be oriented into an antianatomic fashion (A and B).
Ischemic mitral regurgitation: Chordal-sparing mitral valve replacement
Figure 7 If a bioprosthetic valve is used, it is imperative that the stents do not impinge into the retained chordae tendineae. In addition, the aortomitral curtain must be left unobstructed by a stent of the bioprosthesis as it can cause obstruction of the left ventricular outflow tract.
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Figure 8 If the mitral annulus is relatively small for the patient’s body surface area (eg, less than valve sizer 27 or 29), or if leaflets of the mitral valve are fibrotic, or the annulus is partially calcified, we remove the valve completely and resuspend the papillary muscles with 4-0 Gore-Tex (W.L. Gore and Associates, Elkton, MD) sutures. The Gore-Tex sutures are passed through the fibrous portions of the muscle and through the mitral annulus at 9 and 7 o’clock and 5 and 3 o’clock positions (A). If the papillary muscle has more than 1 trunk (as is common with the posterior papillary muscle), additional Gore-Tex sutures are used (B). These sutures should be left untied until the mitral valve prosthesis is implanted.
Ischemic mitral regurgitation: Chordal-sparing mitral valve replacement
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Figure 9 After implanting the mitral valve prosthesis, the Gore-Tex sutures are passed through the sewing ring of the valve and the 2 arms of the sutures are tied together. Here again it is extremely important not to create excessive tension on the papillary muscles. The Gore-Tex sutures should exert mild pull on the papillary muscles in the relaxed heart.
Discussion Mitral valve replacement with preservation of the chordae tendineae reduces operative mortality in comparison with standard mitral valve replacement and may enhance late survival.3,4 As with any operation, mitral valve replacement with retention of the native leaflets can also cause problems when incorrectly applied. The retained chordate/leaflet may affect the opening and closure of implanted mechanical or bioprosthetic valve, and rupture of the papillary muscle due to excessive pull in the chordae tenedineae has also been described.5 However, the attachments between papillary muscles and mitral annulus are believed to be important for ventricular function and they may be even more so in patients with impaired ejection fraction who need mitral valve surgery. Obviously mitral valve repair is the best option because it keeps the ventriculo-annular attachments intact, but because this is not always feasible in patients with ischemic mitral regurgitation and impaired ventricular function, mitral valve replacement with preservation of at least the poste-
rior leaflet is probably the next best approach. We have used this in hundreds of patients over the years and have never encountered complications as described above. As with any other operative procedure, attention to detail is imperative for good outcome.
References 1. Lillehei CW, Levy MJ, Bonnabeau RC Jr: Mitral valve replacement with preservation of papillary muscles and chordae tendineae. J Thorac Cardiovasc Surg 47:532-543, 1964 2. David TE, Uden DE, Strauss HD: The importance of the mitral apparatus in left ventricular function after correction of mitral regurgitation. Circulation 68:II-76-II-82, 1983 3. David TE, Ho W: The effect of preservation of chordae tendineae on mitral valve replacement for post-infarction mitral regurgitation. Circulation 74(suppl I):I-116-I-120, 1986 4. Komeda M, David TE, Rao V, et al: Late hemodynamic effects of the preserved papillary muscles during mitral valve replacement. Circulation 90:II190-II194, 1994 5. Lemke P, Roth M, Kraus B, et al: Ruptured papillary muscle after mitral valve replacement with preservation of chordae tendineae. Ann Thorac Surg 72:1384-1386, 2001
I
n 1964, Lillehei and colleagues introduced the concept of preservation of the attachments between the papillary muscles and mitral annulus during mitral valve replacement to prevent postoperative left ventricular dysfunction.1 This concept was challenged by other investigators and largely abandoned until 1983 when we reexamined the issue and
Division of Cardiovascular Surgery of Peter Munk Cardiac Centre at Toronto General Hospital and University of Toronto, Toronto, Ontario Canada. Dr. David reports receiving lecture fees from Medtronic and St. Jude Medical. Address reprint requests to Tirone E. David, MD, 200 Elizabeth Street 4N457, Toronto, Ontario M5G 2C4, Canada. E-mail: tirone.david@ uhn.ca
194
1522-2942/$-see front matter © 2012 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1053/j.optechstcvs.2012.04.003
found that the attachments between the papillary muscles and mitral annulus were important for postoperative ventricular function in patients with mitral insufficiency.2 This can be accomplished when the mitral insufficiency is corrected by means of mitral valve repair or mitral valve replacement with preservation of the chordae tendineae.2 We also found that mitral valve replacement with preservation of chordae tendineae reduced operative mortality and enhanced late survival in patients with ischemic mitral insufficiency.3 This article describes the technique we have used to preserve the attachments between the papillary muscles and mitral annulus during mitral valve replacement for ischemic mitral insufficiency.
Ischemic mitral regurgitation: Chordal-sparing mitral valve replacement
Operative Technique
Figure 1 Because patients with ischemic mitral insufficiency frequently require concomitant myocardial revascularization, full median sternotomy is the usual approach to the heart. Cardiopulmonary bypass is established by cannulating the ascending aorta and both cavae through the right atrium. During the aortic clamping, the myocardium is protected with cold blood cardioplegia delivered intermittently through the aortic root and coronary sinus. The coronary arteries are bypassed before repairing or replacing the incompetent mitral valve. The left atrium is opened widely starting at the interatrial groove and extending to the dome of the atrium behind the superior vena cava and inferiorly toward the left inferior pulmonary vein and parallel to the coronary sinus. IVC ⫽ inferior vena cava; SVC ⫽ superior vena cava.
195
T.E. David
196
Figure 2 The majority of patients with ischemic mitral regurgitation have thin and pliable mitral valve leaflet. If the mitral valve is to be replaced and the mitral annulus is dilated, a triangular resection of the anterior leaflet (A) is performed, leaving all chordae tendineae attached to the ventricular surface of the remnants of the anterior leaflet (B).
Ischemic mitral regurgitation: Chordal-sparing mitral valve replacement
Figure 3 Multiple interrupted inverting sutures of 2-0 polyester with pledgets are passed through the mitral annulus approximately 3-4 mm from the free margins of the posterior leaflet. It is important to keep all chordae tendineae taut but not excessively so as to apply undue tension on the papillary muscles.
197
198
T.E. David
Figure 4 In the commissural areas the sutures are passed through the annulus first and then through the remnants of the anterior leaflet 5-9 mm from its free margin to avoid excessive tension of the strut chords that are inserted on the ventricular side of the anterior leaflet, a few millimeters from the free margin (A). If the remnants cannot be folded on the annulus safely because the strut chords are too short, it is safer to resect the anterior leaflet entirely and preserve only the posterior leaflet and some commissural chordae (B).
Ischemic mitral regurgitation: Chordal-sparing mitral valve replacement
Figure 5 Once all annular sutures are through the mitral annulus and leaflets, they are then passed through the sewing ring of a prosthetic heart valve. The prosthetic heart valve must not be larger than the annulus and it is safer to be slightly smaller than the size of the mitral annulus.
199
200
T.E. David
Figure 6 The sutures are evenly distributed in the sewing ring of mechanical valve and the ends are tied (A). If a bileaflet mechanical valve is used, the leaflets should be oriented into an antianatomic fashion (A and B).
Ischemic mitral regurgitation: Chordal-sparing mitral valve replacement
Figure 7 If a bioprosthetic valve is used, it is imperative that the stents do not impinge into the retained chordae tendineae. In addition, the aortomitral curtain must be left unobstructed by a stent of the bioprosthesis as it can cause obstruction of the left ventricular outflow tract.
201
202
T.E. David
Figure 8 If the mitral annulus is relatively small for the patient’s body surface area (eg, less than valve sizer 27 or 29), or if leaflets of the mitral valve are fibrotic, or the annulus is partially calcified, we remove the valve completely and resuspend the papillary muscles with 4-0 Gore-Tex (W.L. Gore and Associates, Elkton, MD) sutures. The Gore-Tex sutures are passed through the fibrous portions of the muscle and through the mitral annulus at 9 and 7 o’clock and 5 and 3 o’clock positions (A). If the papillary muscle has more than 1 trunk (as is common with the posterior papillary muscle), additional Gore-Tex sutures are used (B). These sutures should be left untied until the mitral valve prosthesis is implanted.
Ischemic mitral regurgitation: Chordal-sparing mitral valve replacement
203
Figure 9 After implanting the mitral valve prosthesis, the Gore-Tex sutures are passed through the sewing ring of the valve and the 2 arms of the sutures are tied together. Here again it is extremely important not to create excessive tension on the papillary muscles. The Gore-Tex sutures should exert mild pull on the papillary muscles in the relaxed heart.
Discussion Mitral valve replacement with preservation of the chordae tendineae reduces operative mortality in comparison with standard mitral valve replacement and may enhance late survival.3,4 As with any operation, mitral valve replacement with retention of the native leaflets can also cause problems when incorrectly applied. The retained chordate/leaflet may affect the opening and closure of implanted mechanical or bioprosthetic valve, and rupture of the papillary muscle due to excessive pull in the chordae tenedineae has also been described.5 However, the attachments between papillary muscles and mitral annulus are believed to be important for ventricular function and they may be even more so in patients with impaired ejection fraction who need mitral valve surgery. Obviously mitral valve repair is the best option because it keeps the ventriculo-annular attachments intact, but because this is not always feasible in patients with ischemic mitral regurgitation and impaired ventricular function, mitral valve replacement with preservation of at least the poste-
rior leaflet is probably the next best approach. We have used this in hundreds of patients over the years and have never encountered complications as described above. As with any other operative procedure, attention to detail is imperative for good outcome.
References 1. Lillehei CW, Levy MJ, Bonnabeau RC Jr: Mitral valve replacement with preservation of papillary muscles and chordae tendineae. J Thorac Cardiovasc Surg 47:532-543, 1964 2. David TE, Uden DE, Strauss HD: The importance of the mitral apparatus in left ventricular function after correction of mitral regurgitation. Circulation 68:II-76-II-82, 1983 3. David TE, Ho W: The effect of preservation of chordae tendineae on mitral valve replacement for post-infarction mitral regurgitation. Circulation 74(suppl I):I-116-I-120, 1986 4. Komeda M, David TE, Rao V, et al: Late hemodynamic effects of the preserved papillary muscles during mitral valve replacement. Circulation 90:II190-II194, 1994 5. Lemke P, Roth M, Kraus B, et al: Ruptured papillary muscle after mitral valve replacement with preservation of chordae tendineae. Ann Thorac Surg 72:1384-1386, 2001